Publication details
Ab Initio investigation of intricate ferrimagnetic states in iron oxide nanoparticles
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| Year of publication | 2024 |
| Type | Conference abstract |
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| Citation | |
| Description | Maghemite (?-Fe2O3) is a ferrimagnetic iron oxide that crystallizes in an inverse spinel structure, notable for its biocompatibility and low cytotoxicity. It can be viewed as magnetite (Fe3O4) with the introduction of iron vacancies into the octahedral sublattice. While the magnetic behavior of maghemite and magnetite is similar, magnetite exhibits a higher total magnetic moment. Iron oxide nanoparticles related to maghemite have numerous applications, including advanced contrast agents for magnetic resonance imaging, carriers for targeted drug delivery, and heat sources for localized magnetic hyperthermia treatment, among many other profitable uses. These arise from the combination of their unique magnetic properties (high saturation magnetization, low coercivity) and small size. Although their applications are well studied, a deeper understanding of the structure-property relationship is still highly desired. This motivates our study, in which we employ density functional theory (DFT) calculations to investigate the properties of iron oxide nanoparticles. Our nanoparticle models are based on bulk maghemite (?-Fe2O3), where tetrahedrally and octahedrally coordinated Fe sublattices exhibit opposing magnetic moment orientations. Notably, our findings revealed that the surfaces of the nanoparticles generate significantly more intricate magnetic states compared to the magnetic arrangements observed in bulk maghemite or magnetite. These intricate magnetic states are characterized by what we term "nested" ferrimagnetism, where Fe atoms exhibit locally opposing magnetic moments even within the same (tetrahedral or octahedral) sublattice. |